Warm extremes in Earth’s climate becoming more common

Study argues increasingly severe events are the new normal.

When you see a lot of sixes coming up on a friend’s Monopoly dice, you might begin to harbor a suspicion that the dice are loaded. But if you see sevens appear, you know something is definitely amiss.

Many scientists have used the analogy of loaded dice when they talk about how weather extremes would change in a warming climate, where the loading of the dice would become apparent over time. So, were recent extreme events like the suffocating 2010 Moscow heat wave or the 2011 Texas drought the product of loaded climate dice?

The immediate cause of each was a meteorological event, such as the “blocking high” that kept the hot weather over Moscow for so long. However, a new study led by NASA’s James Hansen argues that “we can say with high confidence that such extreme anomalies would not have occurred in the absence of global warming.” These basic meteorological events are not uncommon, the study says, but the extreme aspects were made possible by the underlying climate.

The conclusion comes from an analysis of how climate variability has changed since the 1950s. The analysis focuses on the Northern Hemisphere summer months of June, July, and August. This is partly because the winter season is inherently more variable (which makes it harder to detect changes), and partly because longer and warmer summers lead to the kind of extreme droughts and heat waves that have major impacts. (The Northern Hemisphere summer also covers a much larger land mass, where seasonal swings are large, than does the Southern Hemisphere summer.)

The relatively steady climate from 1951 to 1980 is used as the baseline for comparison; since then, the climate has warmed nearly 0.6°C (1.1°F). Over that time, temperatures fell pretty nicely along a bell curve. Extreme warm (or cool) summer weather, lying more than three standard deviations away from the average, were present over less than one percent of the globe at any given time. Moving toward the present, however, the analysis shows the bell curve becoming a bit wider and shifting toward warmer temperatures, meaning that three-standard-deviation warmth now occurs over roughly ten percent of the globe.

The open access paper is unusual in that it is clearly written to be understandable to the general public, and is obviously aimed at them. Hansen used his membership in the National Academies of Science to publish the paper, and accompanied its release with an op-ed in the Washington Post.

The paper also makes an appeal to personal experience, suggesting that, while year-to-year variability makes it difficult for people to personally relate to global warming, “a perceptive person old enough to remember the climate of 1951-1980 should recognize the existence of climate change, especially in summer.” The authors also point out that their analysis involves no climate models, and they include material that clearly anticipates objections from those who distrust climate science.

The potential for a broadening of the climate bell curve, leading to more frequent extremes, has been a topic of discussion for some time. This study purports to provide evidence that this is, indeed, already occurring, though some valid concerns about the methods have been raised. If the analysis proves accurate, the implications for the future are obvious. “Additional global warming in the next 50 [years], if business-as-usual fossil fuel emissions continue,” the authors write, “is expected to be at least 1°C. In that case, the further shifting of the anomaly distribution will make [three-standard-deviation] anomalies the norm and [five-standard-deviation] anomalies will be common.” A climate that rolls more sevens—or eights—is an uncomfortable reality to face.

The paper uses the GISS surface air temperature analysis. The brief documentation for that states:

"As there are other potential sources of error, such as urban warming near meteorological stations, etc., many other methods have been used to verify the approximate magnitude of inferred global warming. These methods include inference of surface temperature change from vertical temperature profiles in the ground (bore holes) at many sites around the world...."

So I don't think they're "only getting these temperature readings from stations in major urban areas"

And the pic only shows the US. What about the rest of the world? Is it hotter in Anarctica or colder? And will we be having this crisis in the winter time, when people are skiing on snow or sliding on ice?

I doubt it. Global warming rears its falsehood only in the summertime. When it's supposed to be hot.

"Berkeley Earth also has carefully studied issues raised by skeptics, such as possible biases from urban heating, data selection, poor station quality, and data adjustment. We have demonstrated that these do not unduly bias the results."

And the pic only shows the US. What about the rest of the world? Is it hotter in Anarctica or colder? And will we be having this crisis in the winter time, when people are skiing on snow or sliding on ice?

I doubt it. Global warming rears its falsehood only in the summertime. When it's supposed to be hot.

The author probably just picked that picture for the article. I'm astonished how people still ignore the fact that the earth HAS globally warmed in the past 60 years despite all the statistical information presented to them. You can still argue the cause of the warming if you'd like, but denying that it has warmed is just sticking your head in the sand. You can run for political office; you'd fit right in.

And the pic only shows the US. What about the rest of the world? Is it hotter in Anarctica or colder? And will we be having this crisis in the winter time, when people are skiing on snow or sliding on ice?

I doubt it. Global warming rears its falsehood only in the summertime. When it's supposed to be hot.

Read the article, it answers all your questions.

Quote:

The conclusion comes from an analysis of how climate variability has changed since the 1950s. The analysis focuses on the Northern Hemisphere summer months of June, July, and August. This is partly because the winter season is inherently more variable (which makes it harder to detect changes), and partly because longer and warmer summers lead to the kind of extreme droughts and heat waves that have major impacts. (Northern Hemisphere summer also covers a much larger land mass, where seasonal swings are large, than does Southern Hemisphere summer.)

The point of the paper is that the recent frequency of unusual weather events is extremely improbable without assuming a changing climate. It isn't claiming that impossible or unprecedented events have been occurring, which is what rolling a 7 would be.

The paper also makes an appeal to personal experience, suggesting that, while year-to-year variability makes it difficult for people to personally relate to global warming, “a perceptive person old enough to remember the climate of 1951-1980 should recognize the existence of climate change, especially in summer.”

When a season is cool its just weather, not evidence against climate change. However when a season supports our theory we'll "appeal to personal experience."

And will we be having this crisis in the winter time, when people are skiing on snow or sliding on ice?

Are you referring to last winter ( http://www.ec.gc.ca/adsc-cmda/default.a ... 3D32A-1#a1 ), where temperatures averaged 3.6°C above normal and percipitation was noticably below average? The third warmest winter since 1948? I don't recall much skiing on snow or sliding on ice at all.

The point of the paper is that the recent frequency of unusual weather events is extremely improbable without assuming a changing climate. It isn't claiming that impossible or unprecedented events have been occurring, which is what rolling a 7 would be.

Two years ago, when we had an unseasonably COLD winter, the global warming crowd was screaming about how weather ≠ climate. Frankly, I believed them then, and I still believe it. One or two years of a heat wave is no more indicative of global climate change than a year of cold was.

But now they're trying to say the hot weather IS indicative of climate change. And they wonder why they don't have any credibility in some circles...

i find it humorous that this paper uses weather as evidence of climate change, when climate change advocates decry that sort of behavior from their opponents extremely stridently.

Just seems a bit hypocritical, is all.

Statistical analyses of trends in weather over time are indicative of climate. The conclusion is not "that drought proves global warming", it's "global warming likely caused that drought".

which is fine, but they then go on to say: "So, do recent extreme events like the suffocating 2010 Moscow heat wave, or the 2011 Texas drought provide evidence that the climate dice are now loaded?"

Or is that just you, the author? I haven't read the paper, so i don't know if that's lifted from it, but the statement above seems like exactly the sort of thing that would be torn to shreds if it were about blizzards meaning there is no climate change.

Shocked how many have taken the George Will "summer's supposed to be hot" argument (and don't get me wrong, I LOVE George Will on pretty much everything except climate change). I believe there's a place for healthy, informed skepticism when it comes to climate science. But I also think there's a difference between skepticism and denalism. Skepticism is more along the lines of "okay, the planet is getting warmer, but are we sure it's getting rapidly warmer and are we sure it's having destructive, irreversible effects?" whereas the denalism is like Sen. James Inhofe claiming it's all a conspiracy.

Listen, when the CEO of Exxon/Mobil admits the planet is getting warmer and that the cause of climate change is his own product (fossil fuels), then I'm not sure what we're arguing about other than degrees of severity and attribution (what percentage of the temp. increase is man-man vs. nature).

i find it humorous that this paper uses weather as evidence of climate change, when climate change advocates decry that sort of behavior from their opponents extremely stridently.

Just seems a bit hypocritical, is all.

Statistical analyses of trends in weather over time are indicative of climate. The conclusion is not "that drought proves global warming", it's "global warming likely caused that drought".

which is fine, but they then go on to say: "So, do recent extreme events like the suffocating 2010 Moscow heat wave, or the 2011 Texas drought provide evidence that the climate dice are now loaded?"

Or is that just you, the author? I haven't read the paper, so i don't know if that's lifted from it, but the statement above seems like exactly the sort of thing that would be torn to shreds if it were about blizzards meaning there is no climate change.

Okay, I can see how you're reading that. Intended as - were these extreme events examples of a shifting probability.

A lot of these recent extremes have been linked to the changes to the Arctic jet stream. This is not surprising, as the jet stream is affected by the temperature gradient from the Arctic to temperate regions, and the Arctic is altering rapidly thanks to climate change. This will be the big story in Europe and America.

Other extreme events closely related to climate change are instances of unusual rainfall in tropical areas. (Warmer air can hold more moisture.) The big story in the tropics will be rainfall patterns and storm formation.

The whole system of ocean and air currents will shift around as warming increases. The final state is impossible to be sure of, because of the difficulty of predicting runaway feedback. It's not looking good, though.

Surprise!Global warming is pretty serious, but it is simply a distraction for the real problems, are are consuming resources at a very rapid rate in comparison to what the earth can sustain. Especially concerning how we live, the waste we generate... Really Global Warming is simply a result of human's lack of sense when it comes to resource utilization.

"Berkeley Earth also has carefully studied issues raised by skeptics, such as possible biases from urban heating, data selection, poor station quality, and data adjustment. We have demonstrated that these do not unduly bias the results."

So... so *there*.

While I agree that warming is occuring, I have to remark on that sentence from Berkeley. The difference between "do not unduly bias" and "do not bias" is enough for a denier to jump all over. "Unduly" implies that there is bias effecting the results.